1. Field of the Invention
This invention relates to an apparatus for drawing a wire to reduce a cross-section thereof.
2. Prior Art
One conventional wire drawing apparatus 10 shown in FIG. 1 comprises a horizontal elongated frame 11 having front and rear ends 11a and 11b, such wire drawing apparatus being commonly referred to as "drawbench" in the trade. A drawing die 12 is detachably mounted on the top 11c of the frame 11 and disposed intermediate opposite ends thereof. A carriage 13 is mounted on the top 11c of the frame 11 for reciprocable movement along a drawing section 11d of the frame 11 extending between the drawing die 12 and the front end 11a.
A chuck 14 is fixedly secured to one end of the carriage 13 directed toward the drawing die 12. A hook member 15 is mounted on the other end of the carriage 13 for vertical pivotal movement. A drive sprocket 16 is rotatably mounted on the front end 11a of the frame 11 while a driven sprocket 17 is rotatably mounted on the frame 11 at a position below the drawing die 12. A plurality of guide rollers 18 are roratably mounted on the frame 11 and disposed between the drive and driven sprockets 16 and 17. An endless chain 20 extends around the drive and driven sprockets 16 and 17 and is held under an appropriate tension by the guide rollers 18. The drive sprocket 17 is operatively connected to a motor (not shown) for being driven for rotation. The endless chain 20 is composed of two pairs of parallel, longitudinally disposed links 20a and transverse pins 20b interconnecting the links 20a, as shown in FIG. 2. The hook member 15 is adapted to be engaged with a selected one of the pins 20b of the endless chain 20.
For drawing a wire 22, one end of the wire 22 is first processed into a tapered shape, and the wire 22 is placed on the top 11c of a delivery section 11e of the frame 11 with the tapered end passed through the hole of the drawing die 12. Then, the tapered end passing through the hole of the drawing die 12 is clamped by the chuck 14. Then, the hook member 15 is pivotally moved downwardly to engage the pin 20b of the endless chain 20 disposed below the hook member 15, as shown in FIG. 3. The endless chain 20 is driven by the motor to move around the drive and driven sprockets 16 and 17 to move the carriage 13 along the frame 11 toward the front end 11a thereof, so that the wire 22 is pulled through the drawing die 12 to reduce the diameter thereof at a predetermined rate. Then, the wire 22 is detached from the chuck 14. Then, the drawing die 12 is replaced by another die having a hole smaller in diameter than the hole of the die 12. Then, one end of the wire 22 is again processed to reduce its diameter so that the reduced or tapered end can be passed through the drawing die. The second drawing operation is carried out according to the above-mentioned procedure. Usually, the wire is drawn several times in this manner, using drawing dies having holes of different diameters. Thus, the wire is reduced in diameter or cross-section at a predetermined rate each time the drawing operation is carried out. When a wire having a diameter of 20 mm is to be reduced to a diameter of 4 mm at a reduction rate of 20%, the drawing operation must be carried out seven times, and each time the drawing operation is completed, the wire has to be transferred from the drawing section 11d to the delivery section 11e for the next drawing operation. This requires much time and is not efficient. In addition, the wire is liable to be damaged or bent during the transferring thereof. Further, with this conventional drawing apparatus, it is necessary that the delivery section 11e should have a length generally equal to that of the drawing section 11d. Thus, the frame 11 has to be twice the length of the finished wire. As a result, the wire drawing apparatus 10 has a substantially increased overall length and therefore is space-consuming.